Nowadays, wall plates of most refrigerator vans (or the reefer trailer, reefer truck) are usually manufactured by a whole piece of fiber reinforce plastic (FRP), and a few refrigerator vans which require higher strength (such as military refrigerator vans) are made of metal plates (such as aluminum plate or stainless steel plate). On the one hand, the whole piece of FRP is easier to get, so it is more widely-used to manufacture the wall plate, but the wall plate made of FRP has lower strength. On the other hand, since the wall plate of the refrigerator van is much wider than normal metal coiled materials, the whole piece of metal plate for manufacturing the wall plate is not easy to get. Besides, the manufacturing cost is very high.
The conventional process for manufacturing the wall plate of the refrigerator van from metal plate is complex. Firstly, the metal coiled material is uncoiled according to the width of the wall plate, then, the uncoiled plates are arranged side-by-side along the lengthwise direction of the wall plate, and at last connected into a whole wall plate, usually by welding, which guarantees high strength and waterproofness. However, since the metal plate for manufacturing the wall plate is very thin, which is usually 0.5 millimeter (mm) to 1.5 mm, severe welding deformation is easy to appear after the welding process. Especially, the wave deformation is usually generated at the welding line, which affects the flatness of the whole plate and further affects the appearance of the wall plate. Besides, although the wall plate by the conventional process is provided with reinforcing ribs, the wall plate, which is a whole plate after the welding process, is also easy to be deformed during transportation.
Another conventional wall plate of the refrigerator van is manufactured by connecting the metal plates through bolts or rivets. When the bolts or the rivets are used, connecting holes need to be formed on the metal plates by punching. After the body is used for a period of time, the connecting parts are easy to get loose, and moist or water from outside may go into the body from the gap between the bolt or the rivet and the connecting hole to affect the temperature insulating property and increase the weight of the refrigerator van. Furthermore, connecting the metal plates by using the rivets or bolts would affect the flatness of the whole plate and further affect the appearance of the wall plate.
Therefore, the refrigerator van has higher appearance requirement for the wall plate, and all the conventional connecting ways need to process the surface of the wall plate, which may broke the surface of the plate. As a result, the conventional metal plate cannot meet the requirement above.